Examples of Ribosomes in Prokaryotic and Eukaryotic Cells

📚 Quick Study Guide

• 🔬 Ribosomes: Are cellular structures responsible for protein synthesis (translation). They are found in both prokaryotic and eukaryotic cells.
• 🦠 Prokaryotic Ribosomes:
  • 🧬 Smaller in size compared to eukaryotic ribosomes.
  • 🔢 Referred to as 70S ribosomes (Svedberg units).
  • 🧩 Composed of a 50S large subunit and a 30S small subunit.
  • 📍 Found freely floating in the cytoplasm.
• 🌱 Eukaryotic Ribosomes:
  • 🧬 Larger than prokaryotic ribosomes.
  • 🔢 Referred to as 80S ribosomes.
  • 🧩 Composed of a 60S large subunit and a 40S small subunit.
  • 📍 Found freely in the cytoplasm, and bound to the endoplasmic reticulum (ER) and nuclear envelope.
• 🧪 Key Difference: The difference in size and subunit composition is crucial and targeted by certain antibiotics.
• 💡 Function: In both cell types, ribosomes read mRNA and use tRNA to assemble amino acids into proteins.

Practice Quiz

1. Which of the following accurately describes prokaryotic ribosomes?
   1. A. 80S ribosomes composed of 60S and 20S subunits
   2. B. 70S ribosomes composed of 50S and 30S subunits
   3. C. 90S ribosomes composed of 60S and 30S subunits
   4. D. 60S ribosomes composed of 40S and 20S subunits
2. Where are eukaryotic ribosomes NOT found?
   1. A. Cytoplasm
   2. B. Endoplasmic Reticulum
   3. C. Nuclear Envelope
   4. D. Cell Wall
3. What is the main function of ribosomes in both prokaryotic and eukaryotic cells?
   1. A. DNA replication
   2. B. Protein synthesis
   3. C. Lipid synthesis
   4. D. Carbohydrate metabolism
4. Which type of ribosome is larger?
   1. A. Prokaryotic
   2. B. Eukaryotic
   3. C. They are the same size
   4. D. Size varies depending on the organism
5. What are the subunits of the 80S eukaryotic ribosome?
   1. A. 50S and 30S
   2. B. 60S and 20S
   3. C. 60S and 40S
   4. D. 50S and 40S
6. Which of the following is a key difference between prokaryotic and eukaryotic ribosomes that is targeted by some antibiotics?
   1. A. Nucleus presence
   2. B. Cell wall composition
   3. C. Size and subunit composition
   4. D. Presence of mitochondria
7. Where are 70S ribosomes typically found?
   1. A. Only in the nucleus of eukaryotic cells
   2. B. Only in the endoplasmic reticulum of eukaryotic cells
   3. C. In the cytoplasm of prokaryotic cells
   4. D. Bound to the Golgi apparatus in eukaryotic cells